PHOENIX — Josh Hader has the look of a Southern California surfer, with the dirty-blonde, shoulder-length hair, and ink-stained arms, but he’s from a small village in Maryland.

He’s a big-time hunter and avid fisherman, who just happens to love hockey.

He’s a skinny, 6-foot, 180-pound left-handed, 24-year chill dude, but instead of listening to rap, hip-hop or country, he rolls with classic rock, with his walk-up song hitting the charts back when eight-track cassettes dominated.

He’s a pitcher for the Milwaukee Brewers, who’s not a starter, not a closer, or even a setup man, but is helping define the newest, baddest bullpen role in baseball.

“That’s the beautiful thing about Josh,’’ Brewers manager Craig Counsell says. “You can’t put him in a box. You can’t stereotype him, or even try to figure him out. He’s just his own self.

“You just sit back, and appreciate him. And believe me, we’re doing that, every single day.’’

In a season that’s starting to become magical for the Brewers, tied for first place (26-18) in the NL Central despite having four of their starting pitchers on the disabled list, Hader has emerged as perhaps their most dynamic, vibrant and integral player.

Just 11 months ago at Chase Field in Phoenix he was making his major-league debut, and he returned for the first time this week as the nastiest reliever in the land, whose exploits should be on national stage in July when he’s selected to the All-Star team.

Wearing No. 71 and galloping in from the bullpen with his hair flopping down his back, sometimes singing to himself, stepping to the mound, and then humiliating hitters who dare step to the plate, Hader has struck out more batters than any reliever in Major League Baseball — 50 in just 25 innings. The opposition is hitting .086 and he is striking out 18 batters per nine innings, which would break Aroldis Chapman’s 2014 record.

“Right now, what he’s doing,’’ Brewers GM David Stearns says, “is as good as any reliever in baseball. There are other guys who have done it longer, and have done it more consistently, but what he’s doing right now is as good as anyone.’’

Just a year ago, he was a struggling minor-league starter who had been twice traded, and now he’s an overnight sensation, thanks in part to his feat April 30 in Cincinnati when he became first pitcher in the modern era with eight strikeouts in 2 2/3 innings. He’s the only National League reliever since 1893 — the year the mound was moved 60 feet 6 inches from home plate — to strike out at least three batters in seven consecutive appearances.

“He’s the coolest guy out there,’’ Brewers first baseman Eric Thames said. “Guys like that do so well because there’s so much failure in this game. He’s like, 'You know, I’m going to go out, work hard, do my best, and whatever happens, happens. And when I’m done, I’m going to go hunt, or fish, or listen to music.’’

Well, sometimes, Hader creates his own music, and can even be spotted singing the words to his walk-up song, “Renegade’’ by Styx, which came out in 1979 and has never been more popular in Milwaukee.

“I’m getting a lot of good compliments from my song, it just pumps people up,’’ Hader says. “I mean, it pumps me up, too. I just start singing it myself on the way to the mound.’’

Hader, who used to cut his own hair, a buzz cut before stopping altogether four years ago, skips to the mound almost like Shaggy Rogers in Scooby-Doo, with hitters trying to figure out whether he’s going to be pumping his 93-97 mph fastball, firing a nasty slider, or completely confusing them with his change-up.

The most dangerous facet of Hader is the element of surprise. The opposition keeps gazing into the Brewers’ bullpen, never knowing when he’s going to emerge. He could pop out in the fourth inning, or in the eighth, and face two batters or nine, with 11 of his 15 appearances going longer than one inning.

"There’s no name for it," says Hader of his role. "I guess just an out-getter.’’

It’s the role that Andrew Miller glorified in the Cleveland Indians’ 2016 World Series run, the one that Archie Bradley perfected for the Arizona Diamondbacks, and now it’s Hader who has taken the hybrid position to another level.

Hader was the final acquisition of former Brewers GM Doug Melvin, who was stunned the Astros (and earlier, Orioles) wanted to give him up. Stearns, ironically, was the Astros' assistant GM at the time, and his front office desired outfielder Carlos Gomez and starter Mike Fiers to bolster a franchise chasing its first playoff berth in a decade.

“Look, the Astros happened to make the playoffs that year, and Gomez and Fiers had a meaningful part of it down the stretch,’’ said Stearns, who became the Brewers’ GM six weeks later. “But looking back a few years later, I’m glad to be on this side of it.’’

There may be a time after the season when the Brewers try moving Hader back to the starting rotation. The debate will be whether he’s more valuable in the pen or pitching 180 innings as a starter. It’s no different for the Diamondbacks, with Bradley hoping one day he returns to the starter’s role.

Yet, for now, the Brewers know they have something special going, featuring the best bullpen in baseball, and the man who makes it all come together.

And, perhaps in two months, the Brewers will share him with everyone when he’s on center stage, a 40-minute drive from his hometown, pitching at Nationals Park in the All-Star Game.

“One of my goals was to be perform well enough to be in that game,’’ said Hader, who has pitched only 97 2/3 career innings. “To be back home. On the East Coast. And for all of my friends and family to be there.